Prokaryotic Cells and Bacteria Vocabulary
Bibliographic Data and Editorial Context
These notes are derived from materials published by Kapelusz Luz Editora S.A. It is noted that the photocopying of this material is prohibited under the regulation LEV . The content focuses primarily on binary fission, the diversity of bacteria, and the specific anatomical and functional properties of prokaryotic cells found within the Reino Moneras.
Evolutionary Origins and Distribution of Prokaryotic Life
The earliest cells to manifest on the planet, appearing approximately million years ago, were prokaryotic cells. These cells are exclusively found forming unicellular organisms, such as bacteria and blue-green algae, which are categorized under the Reino Moneras. These organisms are ubiquitous and can be found in virtually all environments, including water, soil, air, and within other living beings. They are also capable of surviving in extreme temperatures. Morphologically, bacteria exhibit various shapes and are characterized by their size, being approximately times smaller than a medium-sized eukaryotic cell. Furthermore, they contain the smallest amount of genetic material relative to other cell types.
Structural Composition and Organelles of the Prokaryotic Cell
A prokaryotic cell is composed of several distinct parts that facilitate its survival and interaction with the environment. The Pared celular (Cell wall) is located outside the plasma membrane. It is a hard structure that provides mechanical protection to the bacteria and maintains its specific shape. It features pores that allow for the exchange of substances with the external environment, a process regulated by the underlying membrane. The Membrana plasmática (Plasma membrane) functions as a selective barrier that controls the transit of substances from the cytoplasm to the external medium, facilitating the circulation of nutrients and the removal of cellular wastes.
Internally, the Citoplasma (Cytoplasm) of prokaryotic cells does not contain internal membranes (organelles with membranes). Instead, the ADN (DNA) is found coiled and floating freely within the cytoplasm alongside Ribosomas (Ribosomes). The Ribosomas are specialized structures responsible for the production of proteins. For locomotion, many bacteria, particularly those residing in aquatic environments, possess a Flagelo (Flagellum). This structure is essential for the movement and displacement of the cell through liquid media.
Biological Processes: Nutrition, Locomotion, and Reproduction
Bacteria employ diverse strategies for nutrition. Some bacteria are autotrophic and perform photosynthesis to produce their own food. Conversely, other bacteria are heterotrophic and feed on the organic remains of other living beings. The reproductive cycle of bacteria is remarkably rapid, with a single bacterium typically producing two daughter cells approximately every minutes. This reproductive process, known as bipartición celular or fisión binaria (binary fission), begins with the duplication of all internal components. The cell then increases in size, and the components are distributed into two equal parts. During the final stage of binary fission, the cell membrane begins to invaginate or move inward until the two daughter cells, which are practically identical to the mother cell, separate.
Bacterial Diversity: Health, Industry, and Environment
While some bacteria are pathogenic and cause diseases such as meningitis, otitis, and neumonía (pneumonia), many others are essential for life and human industry. Certain bacteria live in symbiotic relationships with other organisms, providing mutual benefits. Examples include the flora intestinal (intestinal flora) in humans, such as the bacterium Escherichia coli, and bacteria that live in association with the roots of specific plants.
In human industry, bacteria are utilized to produce yogurt and cheeses, and are critical in the manufacturing of antibiotics, the decontamination of lakes, and the production of vaccines. Environmentally, bacteria inhabiting the soil play a vital role in plant growth by fixing nitrogen from the air into the ground. In prokaryotic unicellular organisms, the single cell that constitutes the organism is responsible for performing every function necessary for the life of the being.
Questions and Discussion
Research the specific functions of our flora intestinal (intestinal flora) and identify other locations in the human body where bacteria coexist with us.
Consult Chapter of the textbook to investigate the detailed characteristics of the Reino Moneras.